Quantum Bayesianism and the embodied agent

In this presentation, Dr. Jacques Pienaar discusses the notion of an embodied agent in the context of Quantum Bayesianism ('QBism,' for short). QBism is an interpretation of quantum mechanics according to which the wave function represents simply what we know about reality—a kind of betting strategy about what we will see next—as opposed to reality itself.

https://phys.org/news/2023-03-qbism-quan...ityit.html

Ruediger Schack

According to QBism, an approach developed by Christopher Fuchs and me, the great lesson of quantum mechanics is that the usual starting point of the philosophers is simply wrong. Quantum mechanics does not describe reality as it is by itself. Instead, it is a tool that helps guide agents immersed in the world when they contemplate taking actions on parts of it external to themselves.

QBism has also led to a fruitful dialogue with the kindred philosophical schools of thought of pragmatism and phenomenology. Its vision of the world is one in which agents possess genuine freedom and respect each other's autonomy. I like to think that this is what quantum mechanics has been trying to tell us about reality all along.

In conversation with Prof. Christopher A. Fuchs, Essentia Foundation's Hans Busstra explores QBism: an interpretation of quantum mechanics that puts the agent right at the centre. QBism regards quantum theory as just a ‘tool’ agents use and disclaims ontic interpretations of Schrödinger's wave function: the quantum state is not something ‘real,' but instead just our description of, or even our beliefs about, nature. Once known as Quantum Bayesianism, Fuchs has redefined QBism more radically as: 'Quantum Bettabilitarianism.' As agents, we make ‘bets’ on the behavior of the universe in its interactions with us. Though QBism does not equal analytical idealism, in this conversation we touch upon a striking similarity: namely, that pure experience (i.e. phenomenal consciousness) is what quantum theory points to as fundamental in nature. And this, in turn, has implications for how we look upon the meaning of life. In Fuchs' words: quantum theory gives meaning to life.

00:00 Introduction
01:30 Some opening remarks on experience and 'nature striking back'
04:27 Chris Fuchs on the definition of QBism
05:12 Was Copernicus wrong? Why QBism is a free fall
06:46 On Cubism in art and QBism in quantum theory
09:24 The metaphysical debate within quantum mechanics
11:04 What is QBism?
14:23 We bet on the behavior of the universe with us
15:51 What is an agent, an observer, a decision maker?
16:53 Quantum theory is just a manual that agents use
18:10 Chris Fuchs on his mentor John Wheeler
20:24 The participatory universe
20:57 The broken glass between observer and observed
21:50 There is no physical reality prior to measurement
22:18 Back in the quantum museum...
23:37 Chris Fuchs on the different interpretations of the wave function
25:02 Agents perform 'actions': measurement is a term we shouldn't use anymore
26:29 Must an electron 'obey' our gambles on it?
27:36 The multiverse is a dead universe
30:05 The many worlds interpretation wants to uphold determinism
32:03 Genuine novelty comes into the world, the universe is being created on the fly
33:02 From the abstract to the concrete: QBism in practice
38:16 Is QBism doing best in progressing quantum physics?
41:47 The solipsist critique: how to account for a shared world?
44:33 Order in the universe is placed there by us, by the human mind
45:38 What is the ontology of QBism?
47:24 The stuff of the world is neither mind nor matter
50:21 QBism in relationship to analytical idealism
53:06 Can quantum mechanics tell us something about the meaning of life?
58:09 A personal conclusion of the interviewer